U.S. patent number 8,999,117 [Application Number 12/398,070] was granted by the patent office on 2015-04-07 for process and system for heating or cooling streams for a divided distillation column.
This patent grant is currently assigned to UOP LLC. The grantee listed for this patent is Jibreel A. Qafisheh, Michael A. Schultz, Xin X. Zhu. Invention is credited to Jibreel A. Qafisheh, Michael A. Schultz, Xin X. Zhu.
United States Patent |
8,999,117 |
Schultz , et al. |
April 7, 2015 |
Process and system for heating or cooling streams for a divided
distillation column
Abstract
One exemplary embodiment can be a system for separating a
plurality of naphtha components. The system can include a column,
an overhead condenser, and a side condenser. Generally, the column
includes a dividing imperforate wall with one surface facing a feed
and another surface facing at least one side stream. Typically, the
wall extends a significant portion of the column height to divide
the portion into at least two substantially vertical, parallel
contacting sections. Typically, the overhead condenser receives an
overhead stream including a light naphtha from the column. Usually,
a side condenser receives a process stream from the column and
returns the stream to the column to facilitate separation. A
cooling stream may pass through the overhead condenser and then the
side condenser.
Inventors: |
Schultz; Michael A. (Des
Plaines, IL), Zhu; Xin X. (Des Plaines, IL), Qafisheh;
Jibreel A. (Des Plaines, IL) |
Applicant: |
Name |
City |
State |
Country |
Type |
Schultz; Michael A.
Zhu; Xin X.
Qafisheh; Jibreel A. |
Des Plaines
Des Plaines
Des Plaines |
IL
IL
IL |
US
US
US |
|
|
Assignee: |
UOP LLC (Des Plaines,
IL)
|
Family
ID: |
42677276 |
Appl.
No.: |
12/398,070 |
Filed: |
March 4, 2009 |
Prior Publication Data
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Document
Identifier |
Publication Date |
|
US 20100224536 A1 |
Sep 9, 2010 |
|
Current U.S.
Class: |
202/161; 202/159;
202/270 |
Current CPC
Class: |
B01D
3/14 (20130101); B01D 3/141 (20130101); C10G
2400/02 (20130101) |
Current International
Class: |
B01D
3/32 (20060101) |
Field of
Search: |
;202/159,161,270 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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WO-2005/046831 |
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May 2005 |
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WO |
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WO-2008/091317 |
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Jul 2008 |
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WO |
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Other References
R Agrawal, Multicomponent Distillation Columns with Partitions and
Multiple Reboilers and Condensers, 40 Ind. Eng. Chem. Res.
4258-4266 (2001). cited by examiner .
Poth, Abstract of Minimal Energy Requirements of Dividing Wall
Columns, 2004. cited by applicant .
Christiansen et al., Complex Distillation Arrangements: Extending
the Petlyuk Ideas, Computers and Chemical Engineering, May 1997,
vol. 21, No. Suppl. 1, pp. S237-S242. cited by applicant .
Ivanescu et al., Dividing Wall Column--a New Challenge for
Separation Systems, 2004, p. 4. cited by applicant .
Lestak et al., Advanced Distillation Saves Energy and Capital,
Chemical Engineering, Jul. 1997, vol. 104, No. 7, pp. 72-76. cited
by applicant .
Mueller et al., Reactive Distillation in a Dividing Wall Column:
Rate-Based Modeling and Simulation, Industrial and Engineering
Chemistry Research, 2007, vol. 46, No. 11, pp. 3709-3719. cited by
applicant .
Mueller et al., Rate-Based Analysis of Reactive Distillation
Sequences with Different Degrees of Integration, Chemical
Engineering Science, 2007, vol. 62, No. 24, pp. 7327-7335. cited by
applicant .
Muralikrishna et al., Development of Dividing Wall Distillation
Column Design Space for a Specified Separation, Chemical
Engineering Research and Design, Mar. 2002, vol. 80, No. 2, pp.
155-166. cited by applicant .
Poth et al., Minimal Energy Requirements of Dividing-Wall Columns,
Chemie-Ingenieur-Technik, 2004, vol. 76, No. 12, pp. 1811-1814.
cited by applicant .
Serra et al., Controllability of Different Multicomponent
Distillation Arrangements, Apr. 16, 2003, vol. 42, No. 8, pp.
1773-1782. cited by applicant .
Serra et al., Dynamic Behavior and Controllability Issues in the
Design and Operation of the Dividing Wall Column, Czech Society of
Chemical Engineering 13th International Chemical and Process
Engineering CHISA 98 Congress, 1998, vol. N.F1.5, p. 20. cited by
applicant .
Slade et al., Dividing Wall Column Revamp Optimises Mixed Xylenes
Production, 2006, AICHE the 2006 Spring National Meeting, Orlando,
FL, p. 6. cited by applicant .
Suphanit et al., Exergy Loss Analysis of Heat Transfer Across the
Wall of the Dividing-Wall Distillation Column, Energy, 2007, vol.
32, No. 11, pp. 2121-2134. cited by applicant.
|
Primary Examiner: Boyer; Randy
Claims
The invention claimed is:
1. A system for separating a plurality of naphtha components,
comprising: a column, comprising: a dividing imperforate wall with
one surface facing a feed and another surface facing at least one
side stream wherein the wall extends a significant portion of the
column height to divide the portion into at least two substantially
vertical, parallel contacting sections; an overhead condenser
receiving an overhead stream from the column; and a side condenser
receiving a process stream from a side draw from the column at a
point above the at least one side stream and the dividing
imperforate wall and returning the stream to the column to
facilitate separation; wherein a cooling stream passes through the
overhead condenser and then the side condenser.
2. The system according to claim 1, wherein the column further
comprising: a reboiler receiving at least a portion of a bottom
stream and returning that portion to the column; and a side
reboiler receiving another process stream from the column and
returning the another process stream to the column.
3. The system according to claim 2, further comprising a heating
stream passing through the reboiler and then the side reboiler.
4. The system according to claim 1, wherein the at least one side
stream comprises a first side stream comprising a medium naphtha
and a second side stream comprising an aromatic naphtha.
5. The system according to claim 2, wherein the bottom stream
comprises a heavy naphtha.
6. The system according to claim 1, wherein the cooling stream
comprises cooling water.
7. The system according to claim 3, wherein the heating stream
comprises high pressure steam.
8. A system for separating a plurality of naphtha components,
comprising: a first column, comprising: a dividing imperforate wall
with one surface facing a feed and another surface facing a side
stream wherein the wall extends a significant portion of the column
height to divide the portion into at least two substantially
vertical, parallel contacting sections; a reboiler; and a side
reboiler receiving a process stream from a side draw from the
column at a point below the side stream and below the dividing
imperforate wall; wherein a heating stream passes through the
reboiler and the side reboiler.
9. The system according to claim 8, wherein the heating stream
comprises a light cycle oil.
10. The system according to claim 8, wherein the first column
further comprises an overhead condenser and a side condenser
wherein a cooling stream passes through the overhead condenser and
then the side condenser.
11. The system according to claim 10, wherein the cooling stream
comprises cooling water.
12. The system according to claim 10, wherein the first column
provides an overhead stream comprising a light naphtha.
13. The system according to claim 10, wherein the first column
provides a side stream comprising a medium naphtha.
14. The system according to claim 10, further comprising a second
column communicating with the first column so as to provide a feed
to or receive a feed from the first column wherein the second
column is non-divided and provides an overhead stream comprising an
aromatic naphtha.
15. The system according to claim 10, further comprising a second
column communicating with the first column so as to provide a feed
to or receive a feed from the first column wherein the second
column is non-divided and provides a bottom stream comprising a
heavy naphtha.
16. A system for separating a plurality of naphtha components,
comprising: a first column, comprising: a dividing imperforate wall
with one surface facing a feed and another surface facing a side
stream wherein the wall extends a significant portion of the column
height to divide the portion into at least two substantially
vertical, parallel contacting sections; an overhead condenser
receiving an overhead stream from the column; a side condenser
receiving a process stream from a first side draw from the column
at a point above the side stream and returning the stream to the
column to facilitate separation; a reboiler; and a side reboiler
receiving a process stream from a second side draw from the column
at a point below the side stream and returning the stream to the
column to facilitate separation; wherein the first side draw is
above the second side draw.
17. The system according to claim 16, wherein a heating stream
passes through the reboiler and the side reboiler.
18. The system according to claim 16, wherein the first column
further comprises an overhead condenser and a side condenser
wherein a cooling stream passes through the overhead condenser and
then the side condenser.
19. The system according to claim 18, wherein the cooling stream
comprises cooling water.
20. The system according to claim 18, wherein the first column
provides an overhead stream comprising a light naphtha.
Description
FIELD OF THE INVENTION
This invention generally relates to a divided distillation column,
and condensing and heating duties relating thereto.
DESCRIPTION OF THE RELATED ART
In some instances, a dividing wall column can be more efficient for
separating three or more products from a feed. Particularly, in
some instances a dividing wall column can be used instead of two or
more conventional distillation columns. Thus, the single dividing
wall column can provide energy and capital savings as compared to a
plurality of conventional columns that are utilized to obtain the
same separation.
However, an individual dividing wall column typically requires all
of the heating supplied at a maximum temperature and all of the
cooling supplied at a minimum temperature. Generally, providing
these conditions at high and low temperatures requires expensive
utilities, such as high pressure steam, available in a refinery or
a chemical manufacturing facility. On the other hand, a series of
conventional distillation columns can have intermediate duties
supplied, which can be provided by lower cost utilities, such as
medium pressure steam, which can be less expensive. Consequently,
efficiently utilizing heating and/or cooling streams to obtain the
requisite duty requirements of a dividing wall column would be
highly desirable.
SUMMARY OF THE INVENTION
One exemplary embodiment can be a system for separating a plurality
of naphtha components. The system can include a column, an overhead
condenser, and a side condenser. Generally, the column includes a
dividing imperforate wall with one surface facing a feed and
another surface facing at least one side stream. Usually, the wall
extends a significant portion of the column height to divide the
portion into at least two substantially vertical, parallel
contacting sections. Typically, the overhead condenser receives an
overhead stream including a light naphtha from the column. Usually,
a side condenser receives a process stream from the column and
returns the stream to the column to facilitate separation. A
cooling stream may pass through the overhead condenser and then the
side condenser.
Another embodiment can be a system for separating a plurality of
naphtha components that may include a first column and a second
column. Generally, the first column includes a dividing imperforate
wall with one surface facing a feed and another surface facing a
side stream, a reboiler, and a side reboiler. Usually, the wall
extends a significant portion of the column height to divide the
portion into at least two substantially vertical, parallel
contacting sections. Typically, the second column is non-divided
and communicates with the first column so as to provide a feed to
or receive a feed from the first column. A heating stream can pass
through the reboiler and the side reboiler.
Yet a further embodiment may be a process for utilizing streams for
a plurality of vessels communicating with a divided distillation
column. The process can include passing a heating stream through a
reboiler and the same or a different heating stream through a side
reboiler to reduce the duty required in the reboiler of the divided
distillation column. Typically, the divided distillation column
produces at least two of a light naphtha, a medium naphtha, an
aromatic naphtha, and a heavy naphtha.
Thus, the embodiments disclosed herein can provide mechanisms for
efficiently providing increased reboiling and condensing duties. As
an example, a stream can be withdrawn from the column to a side
reboiler, and utilizing a lower temperature steam or a process
stream can reduce the amount of high temperature steam required for
a bottom reboiler of the column. As a consequence, the embodiments
disclosed herein can provide greater energy efficiency to further
reduce the operating costs of a dividing wall column.
DEFINITIONS
As used herein, the term "stream" can be a stream including various
hydrocarbon molecules, such as straight-chain, branched, or cyclic
alkanes, alkenes, alkadienes, and alkynes, and optionally other
substances, such as gases, e.g., hydrogen, or impurities, such as
heavy metals, and sulfur and nitrogen compounds. The stream can
also include aromatic and non-aromatic hydrocarbons. Moreover, the
hydrocarbon molecules may be abbreviated C1, C2, C3 . . . Cn where
"n" represents the number of carbon atoms in the one or more
hydrocarbon molecules.
As used herein, the term "zone" can refer to an area including one
or more equipment items and/or one or more sub-zones. Equipment
items can include one or more reactors or reactor vessels, heaters,
exchangers, pipes, pumps, compressors, and controllers.
Additionally, an equipment item, such as a reactor, dryer, or
vessel, can further include one or more zones or sub-zones.
As used herein, the term "dividing wall column" generally means a
column including a substantially fluid tight vertical wall
extending through a significant portion of the column's height and
located in a central portion of the column. Thus, a central portion
of the column can be divided into at least two vertical, parallel
vapor-liquid contacting sections. The top and bottom of the wall
terminate in the column at a point distant from the respective end
of the column such that there is open communication across the
column interior at the top and bottom of the dividing wall.
As used herein, the term "non-divided column" generally means a
column absent a dividing wall positioned substantially vertically
within the column dividing a central portion into at least two
vertical, parallel vapor-liquid contacting sections.
As used herein, the term "vapor" can mean a gas or a dispersion
that may include or consist of one or more hydrocarbons.
As used herein, the term "naphtha components" generally means one
or more hydrocarbons with not less than about 10%, by weight,
distilling below about 175.degree. C. and not less than about 95%,
by weight, distilling below about 240.degree. C. in accordance with
ASTM-D86-08.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic depiction of one exemplary system with a
single dividing wall column producing three products.
FIG. 2 is a schematic depiction of another exemplary system of a
single dividing wall column producing four products.
FIG. 3 is a schematic depiction of an exemplary system including a
plurality of columns.
DETAILED DESCRIPTION
Referring to FIG. 1, a system 10 can include a column 100, which
can be a first column 100. The column 100 can have a dividing
imperforate wall 110. Generally, the column 100 can receive a feed
200 and produce an overhead stream 210, at least one side stream
270, and a bottom stream 280. Typically, one surface 114 of the
imperforate wall 110 can face the feed 200 while another surface
116 can face the at least one side stream 270. Typically, a
significant portion 122 of the column height 126 is taken by the
imperforate wall 110. Generally, the imperforate wall 110 divides
the column 100 into at least two vertical, parallel contacting
sections 130, namely a first contacting section 134 and a second
contacting section 138.
The embodiments as described herein can utilize a dividing wall
column either in combination with a non-divided column or alone to
produce at least three or four products. That is, the vapor leaving
the top of each divided section and the liquid leaving the bottom
of each divided section can flow into a common section and be
admixed. Each section often contains fractionation trays and/or
packing intended to promote separation. The feed stream to the
column can enter on a first receiving side of a dividing wall
section of the column. Alternatively, the feed may enter near the
bottom of the receiving section. Exemplary dividing wall columns
are disclosed in, e.g., U.S. Pat. No. 6,551,465 B1 and U.S. Pat.
No. 6,558,515 B1.
Typically, these product streams can include at least one of a
light naphtha (LN), a medium naphtha (MN), an aromatics naphtha
(ARN), a heavy naphtha (HN), or a combination thereof. The boiling
points (BP) and true boiling points (TBP) as determined by ASTM
D2892-05 are depicted in the following table:
TABLE-US-00001 TABLE 1 Product Stream BP (.degree. C.) TBP 10
(.degree. C.) TBP 90 (.degree. C.) LN 20-80 61 MN 80-150 56 102 ARN
150-215 102 158 HN at least about 215 162
The column 100 can also include an overhead condenser 140, a
receiver 150, a side condenser 160, a reboiler 170, and a side
reboiler 180. Generally, the side condenser 160 and/or side
reboiler 180 can provide additional duty capacity to cool or heat
the requisite streams. Particularly, the side condenser 160 can be
at a point above the feed 200 and the at least one side stream 270
and the bottom stream 280. In addition, the side reboiler 180 can
provide additional duty and an intermediate temperature level below
the feed and product stages. Although both a side condenser 160 and
a side reboiler 180 are depicted, it should be understood that only
one of these devices may be incorporated into the column 100. In
addition, while a side condenser 160 is depicted above the dividing
wall 110, it should be noted that the side condenser 160 could be
located at a point above the feed 200 on either the feed side 200
or the product side of the wall 110, but above the side stream 270.
Similarly, the side reboiler 180 could be located at a position on
the feed side or product side of the wall 110 below the feed 200
and above the bottom stream 280.
The duty for the side condenser 160 can be provided by cooling
utilities using any suitable fluid, such as water, or optionally be
used to generate utilities such as steam or hot oil, or heating a
process stream. The duty for a side reboiler 180 can be provided by
utilities such as steam or hot oil, or by a process stream.
Generally, it is also beneficial to use multiple reboiling stages
or condensing stages with a combination of process streams and
utility streams.
In this exemplary embodiment, an overhead stream 210 can pass
through the overhead condenser 140 and then to the receiver 150. A
portion of a light naphtha product 218 can be provided back to the
column as a reflux 214. To provide additional duty, a process
stream or side draw 220 can be withdrawn from the column 100,
passed through the side condenser 160 to be cooled, and returned. A
cooling stream 230 can pass or cascade through the overhead
condenser 140 and the side condenser 160. In this manner, the
cooling stream 230 can be water, such as cooling water, used first
to cool the overhead stream 210 and then the side draw 220. In this
manner, the same utility stream 230 can be used to cool two process
streams to provide additional cooling duty for the column 100.
Below the side stream 270, which is typically a medium naphtha
product, a bottom stream 280 can be withdrawn from the column.
Usually, a portion is a bottom product 288, typically a heavy
naphtha, with another portion as a return 284. The return 284
passes through the reboiler 170. The reboiler can use any suitable
heat source, such as a furnace, high pressure stream, or another
process stream. In addition, another process stream or side draw
250 can receive additional heating duty. Typically, the side draw
250 is withdrawn from the column 100 above the bottom stream 280
and below the side stream 270, passed through the side reboiler
180, and returned. The side reboiler 180 can be located any
suitable elevation on the column 100, such as about half-way
between the bottom of the dividing wall 110 and the bottom tray of
the column 100. Similarly, as described above for the condensers
140 and 160, a heating stream 260 can pass through the reboiler 170
and then the side reboiler 180. Generally, this heating stream 260
can be any suitable heating stream, such as a high pressure steam,
a medium pressure steam, a light cycle oil, or another process
stream. As an example, the heating stream 260 can have an inlet
temperature of the reboiler 170 of about 200-about 220.degree. C.,
an outlet temperature of the reboiler 170 of about 180-about
200.degree. C., and an outlet temperature of the side reboiler 180
of about 165-about 185.degree. C.
As such, utilizing the heating stream 260 through both the reboiler
170 and the side reboiler 180 can allow the use of one heating
stream to provide additional heat duty to the column 100.
Another version of the system 10 is depicted in FIG. 2.
Particularly, the column 100 can receive a feed 300 and provide an
overhead stream 310 including a light naphtha, a plurality of side
streams 370, namely a first side stream 374 including a medium
naphtha, and second side stream 378 including an aromatic naphtha,
and a bottom stream 380 including a heavy naphtha. Generally, the
feed 300 can enter the column 100 and into the area defined by the
dividing wall 110. The lighter material can rise from the column
100 and exit as the overhead stream 310, pass through the overhead
condenser 140 and into the receiver 150. Generally, a portion can
be obtained as a light naphtha product 318 with another part
returned as a reflux 314. In addition, a side draw 320 can be
withdrawn from the column 100, passed through the side condenser
160, and returned. A cooling stream 330 can pass through the
overhead condenser 140 and then the side condenser 160 for
providing cooling duty. The cooling stream 330 can be any suitable
stream, as described above.
The bottom stream 380 can provide a heavy naphtha product 388 with
a portion as a return 384. The return 384 can pass through the
reboiler 170 before providing heat to the bottom of the column 100.
Another side draw 350 can pass through the side reboiler 180 before
being returned to the column 100. Typically, the reboiler 170 and
the side reboiler 180 receive a heating stream 360. The heating
stream 360 can be any suitable stream, as described above. In this
manner, one utility stream can provide the requisite cooling duty
and another process stream can provide the requisite heating duty
for the column 100. This efficient utilization of such process
streams can save energy costs.
Another exemplary version of a system 10 is depicted in FIG. 3.
Particularly, the column 100 is placed in series with a non-divided
column 190. The non-divided column 190 can include a receiver 194
and a reboiler 196.
Generally, the dividing wall column 100 can receive a feed 400 that
may include a plurality of naphtha components. The feed 400 can
provide an overhead stream 410 including a light naphtha, a side
stream 420 including a middle naphtha, and a bottom stream 460 that
can include an aromatic and a heavy naphtha. Generally, as the feed
400 enters the column 100, the lighter material can pass as the
overhead stream 410 passing through the overhead condenser 140 and
then to the receiver 150. A part can be returned as a reflux 414
and another part may be withdrawn as a light naphtha product 418
from the receiver 150. A part of the bottom stream 460 can be
provided as a feed 468 to the second column 190 with another part
as a return 464 to the column 100. Generally, the return 464 can
pass through the reboiler 170 before entering the column 100. In
addition, a side draw 440 can be withdrawn from the column 100,
passed through the side reboiler 180, and returned to the column
100. Generally, any suitable heating stream 450, as described
above, can be used to first heat the reboiler 170, usually having a
higher duty requirement, before being passed to the side reboiler
180. The feed 468 can enter the second column 190. Lighter
materials can exit as an overhead stream 470 passing through an
overhead condenser 192 before entering the receiver 194. A part can
be returned as a reflux 474 with another part withdrawn as an
aromatic naphtha product 478. The heavier material in the column
190 can pass out as a bottom stream 480 with a portion taken as a
heavy naphtha product 488 and another part as a return 484 to the
column 100 which passes through the reboiler 196.
In embodiments discussed above, a single cooling stream can pass in
series through the overhead condenser 140 and then the side
condenser 160, and/or a single heating stream can pass in series
through the reboiler 170 and then the side reboiler 180.
Alternatively, cooling streams and/or heating streams may be used
separately in parallel. As an example referring to FIG. 1, the
system 10 can use separate streams, independently including any
suitable fluid, such as air, water or another process stream, to
pass through the overhead condenser 140 and the side condenser 160.
Similarly, the system 10 can use separate streams, independently
including any suitable fluid, such as high pressure steam, medium
pressure steam, low pressure steam, or another process fluid, to
pass through the reboiler 170 and the side reboiler 180. In one
exemplary version, a high pressure steam can provide heat duty to
the reboiler 170 and a hot light cycle oil stream can provide heat
duty to the side reboiler 180. As such, the amount of high pressure
steam, which can be an expensive utility in a refinery or a
chemical manufacturing unit as compared to other heat sources, can
be reduced.
Without further elaboration, it is believed that one skilled in the
art can, using the preceding description, utilize the present
invention to its fullest extent. The preceding preferred specific
embodiments are, therefore, to be construed as merely illustrative,
and not limitative of the remainder of the disclosure in any way
whatsoever.
In the foregoing, all temperatures are set forth in degrees Celsius
and, all parts and percentages are by weight, unless otherwise
indicated.
From the foregoing description, one skilled in the art can easily
ascertain the essential characteristics of this invention and,
without departing from the spirit and scope thereof, can make
various changes and modifications of the invention to adapt it to
various usages and conditions.
* * * * *